I have the following model that contains a CFA model with zero inflated measures (manifest) variables. I run the model with separate factors, one for the zero inflated process and one for the counts. This is fitted using the EM algorithm and I get good model fit if no other variables or factors are included into the model.
mplusObject(
TITLE = "SEM - main model;",
ANALYSIS = "estimator = mlr;STARTS = 20 5;MITERATIONS=1000;",
VARIABLE = "COUNT ARE x1 (i) x2 (i) x3 (i);",
MODEL = "F1 BY x1 x2 x3;
F2 BY x1#1 x2#1 x3#1;
F1 WITH F2;
F1 ON x6 x7 x8;
F2 ON x6 x7 x8;
",
OUTPUT = "standardized TECH1 TECH8;",
usevariables = colnames(test),
rdata = test)
If I add an additional factor G1
, I seem to get model fit issues. I have tried different factors (different items fed into G1) but this is a setup problem not a data specific issues:
mplusObject(
TITLE = "SEM - main model;",
ANALYSIS = "estimator = mlr;STARTS = 20 5;MITERATIONS=1000;",
VARIABLE = "COUNT ARE x1 (i) x2 (i) x3 (i);",
MODEL = "G1 BY x4 x5;
G1 @1;
F1 BY x1 x2 x3;
F2 BY x1#1 x2#1 x3#1;
F1 WITH F2;
F1 ON x6 x7 x8;
F2 ON x6 x7 x8;
",
OUTPUT = "standardized TECH1 TECH8;",
usevariables = colnames(test),
rdata = test)
Have I setup this incorrectly?
Model fit error messages:
RANDOM STARTS RESULTS RANKED FROM THE BEST TO THE WORST LOGLIKELIHOOD VALUES
5 perturbed starting value run(s) did not converge in the initial stage
optimizations.
Final stage loglikelihood values at local maxima, seeds, and initial stage start numbers:
-3062.407 unperturbed 0
4 perturbed starting value run(s) did not converge.
THE MODEL ESTIMATION TERMINATED NORMALLY
WARNING: THE RESIDUAL COVARIANCE MATRIX (THETA) IS NOT POSITIVE DEFINITE.
THIS COULD INDICATE A NEGATIVE VARIANCE/RESIDUAL VARIANCE FOR AN OBSERVED
VARIABLE, A CORRELATION GREATER OR EQUAL TO ONE BETWEEN TWO OBSERVED
VARIABLES, OR A LINEAR DEPENDENCY AMONG MORE THAN TWO OBSERVED VARIABLES.
CHECK THE RESULTS SECTION FOR MORE INFORMATION.
However, looking at the STD results, there is a negative variance and the factor loadings in G1 are way above 1 (x5)?
STANDARDIZED MODEL RESULTS
STDYX Standardization
Two-Tailed
Estimate S.E. Est./S.E. P-Value
G1 BY
X4 0.106 0.003 32.911 0.000
X5 6.097 0.439 13.900 0.000
F1 BY
AGG 0.296 0.040 7.403 0.000
SIB 0.259 0.040 6.459 0.000
DES 0.292 0.038 7.719 0.000
F2 BY
AGG#1 0.719 0.000 999.000 999.000
SIB#1 0.452 0.096 4.720 0.000
DES#1 0.777 0.000 999.000 999.000
F1 ON
MCHAT 0.352 0.089 3.973 0.000
HQ_TOT 0.097 0.091 1.066 0.286
CSHQ 0.270 0.076 3.526 0.000
F2 ON
MCHAT -0.154 0.096 -1.607 0.108
HQ_TOT 0.114 0.079 1.440 0.150
CSHQ -0.300 0.073 -4.123 0.000
F1 WITH
F2 -0.999 0.001 -1061.904 0.000
Intercepts
x4 1.792 0.074 24.064 0.000
x5 2.297 0.136 16.841 0.000
x1#1 1.357 0.392 3.467 0.001
x1 0.972 0.247 3.943 0.000
x2#1 1.830 0.492 3.717 0.000
x2 0.876 0.244 3.585 0.000
x3#1 2.245 0.426 5.269 0.000
x3 0.855 0.221 3.860 0.000
Variances
G1 1.000 0.000 999.000 999.000
Residual Variances
x4 0.989 0.001 1443.652 0.000
x5 -36.175 999.000 999.000 999.000
F1 0.731 0.081 8.982 0.000
F2 0.877 0.051 17.184 0.000
Unfortunately, I cannot add data to this post.